In the event of a nuclear war, the Pentagon in 1956 penned a report that listed 1,200 cities and 1,100 airfields spread across eastern Europe, the Soviet Union and China that were prioritized for various levels of destruction, should the unthinkable happen. The goals were twofold: deny the former Communist Bloc’s ability to field an effective air force and then destroy its ability to wage a protracted war.

The details of the Pentagon’s plans were recently revealed in the 800-page Strategic Air Command Atomic Weapons Requirements Study for 1959, “the most comprehensive and detailed list of nuclear targets and target systems that has ever been declassified,” according to The National Security Archive, an organization run by George Washington University that published it last week.

The document, written before the age of Intercontinental Ballistic Missiles, or ICBMs, outlines a main effort to initially destroy the Soviet Union’s ability to field their bomber fleet against NATO countries and U.S. interests in Europe.

The first two airbases slotted for destruction, Bykhov and Orsha, are both located in Belarus, while the first two cities targeted are Moscow and Leningrad (modern-day St. Petersburg). In Moscow, the Strategic Air Command picked 175 ‘Designated Ground Zeroes’ or DGZs, while in Leningrad there were 145. The targets ranged from military command centers to “population centers”–such as the suburbs of Leningrad. While each target might not have constituted its own bomb, the DGZs were designed to destroy factories that made basic industrial equipment and medicine. Purposely missing from the recently released study is the amount of nuclear weapons needed to destroy said targets, though the nuclear weapons would have ranged from 1.7 t0 9 megatons to hit “air power” targets (the bomb dropped on Hiroshima, though atomic, was roughly 0.013 megatons). Targets to destroy population centers would have been hit with atomic weapons.

According to William Burr, the author of the National Security Archive’s summary of the report, the Strategic Air Command (or SAC) placed a very high priority on the weapon’s blast effects. To get the largest levels of destruction, the SAC reasoned, the bombs had to explode at surface level (as opposed to an air detonation). This was due in part that, at the time, the Air Force had decided that thermal damage (the heatwave caused by the bomb) and radiation damage were “relatively ineffective.” Aside from greater damage on the ground, a surface burst would create sizable radiation clouds that would travel in whatever direction the wind was blowing upon the weapon’s detonation.

The nuclear weapons would be delivered by aircraft such as the B-47 (based out of the United Kingdom, Morocco and Spain) and the newly introduced B-52 bomber, according to the report. In addition to the aircraft that would use nuclear-loaded cruise missiles, the report also mentioned the Snark, an intercontinental range ground-launched cruise missile that saw limited deployments before being replaced by ICBMs in the early 1960s.